Achievement unlocked —

Standards organization accepts completion of last row of periodic table

Four new elements await their discoverers' choice of names.

Just prior to the end of 2015, the International Union of Pure and Applied Chemistry (IUPAC to everyone, including itself) made a momentous announcement: it was accepting the existence of four new chemical elements. Combined, they complete the bottom row of the periodic table.

These days, discovering a new element involves making it yourself. Moderately weighty atoms are accelerated into each other and, in rare cases, fuse to form a single atomic nucleus—which falls back apart again almost instantly. Between the rarity of the formation and the vanishingly small half-life, actually spotting a success is a significant challenge.

Still, evidence that these four elements have been created was building for a number of years. The IUPAC, however, waited to convene a panel of experts to evaluate that evidence. Clearly, the panel found it compelling.

Credit for element 113 (temporary name: ununtrium, or Uut) goes to Japan's RIKEN. The remaining elements have the placeholders ununpentium, Uup; ununseptium, Uus; and ununoctium, Uuo. They're credited to a collaboration among Russia's Joint Institute for Nuclear Research and the US' Lawrence Livermore and Oak Ridge National Laboratories. These institutions will get to name the new elements, which "can be named after a mythological concept, a mineral, a place or country, a property, or a scientist." So, you can start lobbying for your favorite mythological concept now.

With those elements, the seventh row of the periodic table is now complete. Which would make element 118 a noble gas, if it actually existed for long enough to have a clearly defined state.

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